permissions - Git change default umask when update file

Question

I have a problem with Git. I searched for a solution in Google and in StackOverflow but nothing helps.

The problem is that every time git updates some file in the working directory (when I checkout branches or I merge a branch, etc.) then the file permissions are changed such that the "writable to group" flag is added. And my apache shows "Error 500" for the file if it is writable to group.

Example: I have a file index.php. Permissions are "-rwxr-xr-x". Current (active) branch is master. This file was changed in the branch "develop". I execute "git checkout develop" and the file index.php gets permissions "-rwxrwxr-x" (writable to group is added). And my site stops working. As apache doesn't allow this flag in php files (I don't know why but I can not change this).

Every time when I execute "git checkout develop" I need to execute also "chmod g-w index.php". I don't like to execute two commands (and sometimes I forget to execute this and my site doesn't work).

What can I do to solve this problem? I think this is something related to umask. I did some tricks I found on web, but nothing works.

Thanks.

Answer 1

Quick answer is this shell function to be put in your ~/.profile. An explanation follows.

git(){(umask 0022; command git "$@")}

A umask is property of a process. It is inherited from the parent process and can be changed from inside later. The command to change umask is usually named umask too.

Git has no configuration option for setting its umask, it does not change its umask after it is executed. You have to set Git's umask from outside, let it be inherited from parent process (usually a shell).

Mmm, you seem to dislike the idea that anything except git has changed umask. So let's change it just when executing git.

When a shell executes a line, it takes the first word on the line and tries to find a function of that name. Only if there is none, it tries to locate a command of that name in PATH. The function I've written above is named git, therefore any direct invocation of git now executes it instead of the git command.

The function executes a subshell, changes its umask and executes the git command from inside the subshell. After Git finishes its work, the subshell also exits and the original shell instance will still have the original umask.

However, the function also shows how to bypass itself. If you call git via command git or even /usr/bin/git, the function won't be called. For any decent use this is good enough, though.